Sildenafil sublingual spray formulations

ABSTRACT

The invention is directed to sublingual spray formulations containing sildenafil. The invention is further directed to methods of treating male sexual dysfunction or pulmonary arterial hypertension by administering sublingual spray formulations containing sildenafil to patients in need of such treatments.

FIELD OF THE INVENTION

The invention is directed to sublingual spray formulations containing sildenafil. The invention is further directed to methods for treating male erectile dysfunction or pulmonary arterial hypertension by administering sublingual spray formulations containing sildenafil to patients in need of such treatments.

BACKGROUND OF THE INVENTION

Sildenafil is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). PDE5 is the predominant isozyme that metabolizes cGMP formed in the corpus cavernosum. Sildenafil is thought to enhance the effect of nitric oxide due to its inhibitory effect in the corpus cavernosum. The enhanced effect of nitric oxide therefore increases the cavernosal blood flow in the penis and lungs.

Sildenafil citrate is commercially available as a film coated tablet (Viagra®, available from Pfizer Inc.) for the treatment of erectile dysfunction. However, the reported bioavailability of this formulation is only 40%.

Sildenafil citrate is also commercially available in formulations for the treatment of pulmonary arterial hypertension. One such formulation is a film coated tablet (Revatio®, available from Pfizer Inc.).

“Sublingual” means “under the tongue” and refers to administration of a substance via the mouth in such a way that the substance is rapidly absorbed via the blood vessels under the tongue. A sublingual formulation is desirable because it bypasses hepatic first pass metabolic processes which provide better bioavailability, rapid onset of action, and higher patient compliance. Dysphagia (difficulty in swallowing) is common among in all ages of people and more common in geriatric patients. In terms of permeability, the sublingual area of oral cavity is more permeable than buccal area. Sublingual drug administration is applied in field of cardiovascular drugs, analgesics, steroids, enzymes and barbiturates.

U.S. Pat. No. 6,548,490 is directed to methods for treating erectile dysfunction including sublingually administering a composition that can include sildenafil. This method requires that the composition be in the form of a tablet, cream, ointment or paste. U.S. Pat. No. 8,133,903 discloses a method that includes administering up to 1.5 mg/kg/day of a PDE5 inhibitor, such as sildenafil, for not less than 45 days. This patent, however, also fails to disclose a fast-acting oral spray formulation.

US Patent Application Publication No. 20130059854 discloses a method for mitigating erectile dysfunction by administering a composition orally that can include sildenafil. This formulation requires the use of sucrose fatty acid esters. U.S. Pat. No. 7,758,886 is directed to an aerosol composition including a poorly water-soluble active agent, such as sildenafil. This patent teaches that tyloxapol, polysorbates, vitamin E TPGS, or macrogol-hydroxystearates, and a phospholipid component, are required for administration. U.S. Pat. No. 6,585,958 discloses an aerosol formulation that may contain sildenafil. This formulation, however, requires a pressure-liquefied propellant mixture that includes dinitrogen monoxide and other components. In addition, US Patent Application Publication No. 20130143894 discloses a sildenafil oral spray formulation wherein the pH is from about 1.5 to less than 3.0. This application, however, teaches the use of a polar solvent such as propylene glycol and ethyl alcohol.

While there are various sildenafil formulations currently available, there is still a need in the art for a quick-onset sublingual spray formulation containing sildenafil.

SUMMARY OF THE INVENTION

In one aspect, the present invention is directed to sublingual spray formulation comprising:

-   -   from about 2% w/w to about 35% w/w sildenafil or a salt thereof,         preferably the salt is salt selected from the group consisting         of citrate, hydrochloride, halide, sulfate, phosphate, acetate,         maleate, succinate, ascorbate, carbonate, mesylate and lactate;     -   from about 0.1% w/w to about 70% w/w of a solvent selected from         the group consisting of water, ethanol, glycerin, polyethylene         glycol 400, propylene glycol, and a combination thereof, the         solvent may comprise from about 0.1% w/w to about 50% w/w water,         the solvent may also comprise from about 10% w/w to about 70%         w/w ethanol, the solvent may also comprise from about 1% w/w to         about 30% w/w glycerin, propylene glycol, polyethylene glycol         400 or a combination thereof; and     -   from about 0.1% w/w to about 60% w/w of at least one acid,         preferably diluted hydrochloric acid,         wherein the formulation has a pH from about 2 to about 6.

In another aspect, the formulations of the present invention do not contain a permeation enhancer.

In another aspect, the formulations of the present invention further comprise a permeation enhancer comprising caprylic acid, preferably from about 0.1% w/w to about 10% w/w, more preferably from about 0.1% w/w to about 5% w/w, and most preferably about 2% w/w to about 5 w/w.

In another aspect the permeation enhancer further comprises a second compound selected from the group selected from the group consisting of menthol, limonene, carvone, methyl chitosan, polysorbates, sodium lauryl sulfate, glyceryl oleate, caproic acid, enanthic acid, pelargonic acid, capric acid, undecylenic acid, lauric acid, myristic acid, palmitic acid, oleic acid, stearic acid, linolenic acid, arachidonic acid, benzethonium chloride, benzethonium bromide, benzalkonium chloride (BKC), cetylpyridium chloride, edetate disodium dihydrate, sodium desoxycholate, sodium deoxyglycolate, sodium glycocholate, sodium caprate, sodium taurocholate, sodium hydroxybenzoyal amino caprylate, dodecyl dimethyl aminopropionate, L-lysine, glycerol oleate, glyceryl monostearate, citric acid, peppermint oil and a combination thereof, preferably menthol, more preferably from about 0.1% w/w to about 5% w/w menthol and even more preferably from about 0.1% w/w to about 1% w/w menthol.

In another aspect, the present invention is directed to a propellant free sublingual spray formulation comprising:

from about 5% w/w to about 20% w/w sildenafil or a salt thereof,

from about 35% w/w to about 55% w/w ethanol;

from about 1% w/w to about 40% w/w water;

from about 5% w/w to about 30% w/w glycerin,

from about 5% w/w to about 30% w/w propylene glycol,

from about 5% w/w to about 30% w/w polyethylene glycol 400; and

from about 0.1% w/w to about 60% w/w diluted hydrochloric acid.

In another aspect, the present invention is directed to a propellant free sublingual spray formulation comprising from about 5% w/w to about 25% w/w sildenafil or a salt thereof, from about 30% w/w to about 50% w/w ethanol, from about 1% w/w to about 20% w/w water, an excipient selected from the group consisting of from about 5% w/w to about 30% w/w glycerol or propylene glycol or a combination thereof, from about 1% w/w to about 20% w/w polyethylene glycol 400, from about 0.1% w/w to about 3% w/w menthol, from about 0% w/w to 7.5% w/w caprylic acid, from about 0.075% w/w to about 0.3% w/w flavoring agent, from about 0.15% w/w to about 1.5% w/w sweetener and from about 0.1% w/w to about 50% w/w hydrochloric acid (Normality ranges from 0.5 to 12N) with the pH ranging from about 2 to 5.

In another aspect, the present invention is directed to a propellant free sublingual spray formulation comprising from about 5% w/w to about 20% w/w sildenafil or a salt thereof, from about 40% w/w to about 50% w/w ethanol, from about 2% w/w to about 15% w/w water, an excipient selected from the group consisting of from about 5% w/w to about 15% w/w glycerol or propylene glycol or a combination thereof, from about 1% w/w to about 15% w/w polyethylene glycol 400, from about 0.1% w/w to about 1% w/w menthol, from about 0% w/w to 5% w/w caprylic acid, from about 0.1% w/w to about 0.2% w/w flavoring agent, from about 0.2% w/w to about 1% w/w sweetener and from about 0.1% w/w to about 40% w/w hydrochloric acid (Normality ranges from 0.5 to 12N) with the pH ranging from about 3 to 5.

In another aspect, the present invention is directed to a propellant free sublingual spray formulation comprising from about 16.84% w/w sildenafil or a salt thereof, from about 50% w/w ethanol, from about 6.24% w/w water, an excipient selected from the group consisting of from about 10% w/w glycerol or propylene glycol or a combination thereof, from about 0.5% L-menthol, from about 3.68% caprylic acid, from about 0.15% flavoring agent, from about 0.4% sweetener and from about 12.19% w/w hydrochloric acid (Normality is 3N) with the pH from about 4 or 4.25 or 4.5, preferably 4.5.

In another aspect, the present invention is directed to a propellant free sublingual spray formulation comprising from about 16.84% w/w sildenafil or a salt thereof, from about 50% w/w ethanol, from about 6.24% w/w water, an excipient selected from the group consisting of from about 10% w/w glycerol or propylene glycol or a combination thereof, from about 0.5% L-menthol, from about 0.15% flavoring agent, from about 0.4% sweetener, with no caprylic acid and from about 12.19% w/w hydrochloric acid (Normality is 3N) with the pH from about 3.6 or 4 or 4.25 or 4.5, preferably 3.6.

In another aspect, the present invention is directed to a propellant free sublingual spray formulation comprising about 8% w/w sildenafil or a salt thereof, about 40% w/w ethanol, about 10% w/w glycerol, about 26% w/w water, about 12% w/w diluted hydrochloric acid; and a permeation enhancer comprising 0.5% w/w menthol and 2% w/w caprylic acid.

In another aspect, the present invention is directed to methods for treating male sexual dysfunction comprising administering the formulations of the present invention to a patient, preferably the formulation is administered sublingually via a spray pump at an amount from about 50 to about 400 μL, more preferably from about 100 to about 200 μL.

In a further aspect, the present invention is directed to methods for treating pulmonary arterial hypertension comprising administering the formulations of the present invention to a patient.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1. A Line-plot of Cumulative Permeation of Sildenafil through Porcine Buccal Epithelium.

DETAILED DESCRIPTION

Applicant unexpectedly discovered sublingual sildenafil formulations that have improved bioavailability, a more rapid absorption, and improved storage stability.

In one embodiment, the present invention is directed to sublingual spray formulation comprising:

-   -   from about 2% w/w to about 35% w/w sildenafil or a salt thereof,         preferably the salt is salt selected from the group consisting         of citrate, hydrochloride, halide, sulfate, phosphate, acetate,         maleate, succinate, ascorbate, carbonate, mesylate and lactate;     -   from about 0.1% w/w to about 70% w/w of a solvent selected from         the group consisting of water, ethanol, glycerin, polyethylene         glycol 400, propylene glycol and a combination thereof, the         solvent may comprise from about 0.1% w/w to about 50% w/w water,         the solvent may also comprise from about 10% w/w to about 70%         w/w ethanol, the solvent may also comprise from about 1% w/w to         about 30% w/w glycerin, propylene glycol, polyethylene glycol         400 or a combination thereof; and     -   from about 0.1% w/w to about 60% w/w of at least one acid,         preferably diluted hydrochloric acid,         wherein the formulation has a pH from about 2 to about 6.

In another preferred embodiment, the sublingual spray formulation is a simple solution.

In a preferred embodiment, the sublingual spray formulation comprises from about 5% w/w to about 22% w/w sildenafil or a salt thereof. In a more preferred embodiment, the sublingual spray formulation comprises about 8% w/w, about 10% w/w, about 12% w/w, about 14% w/w, about 15% w/w, about 16% w/w, about 20%, about 22% w/w w/w sildenafil or a salt thereof.

In a one embodiment, the acid is an inorganic acid or an organic acid.

In another embodiment, the acid is an organic acid selected from the group consisting of malic acid, tartaric acid, citric acid, lactic acid, formic acid, acetic acid, succinic acids, and a combination thereof.

In another embodiment, the acid is an inorganic acid selected from the group consisting of hydrochloric acid, hydrobromic acid, hydrofluoric acid, phosphoric acid, sulfuric acid, nitric acid, sulfonic acid, and a combination thereof.

In a preferred embodiment, the acid is an inorganic acid. In a more preferred embodiment, the inorganic acid is hydrochloric acid that is diluted or concentrated.

In one embodiment, the hydrochloric acid is diluted to from about 1N to about 12N. In a preferred embodiment, the hydrochloric acid is diluted to from about 1.5N to about 6N. In a more preferred embodiment, the hydrochloric acid is diluted to about 1.5N or about 3N.

In another embodiment, the formulations contain from about 0.1% w/w to about 50% water. In a preferred embodiment, the formulations contain from about 1% w/w to about 30% w/w water. In another preferred embodiment, the formulations contain from about 1% w/w to about 15% w/w water. In another preferred embodiment, the formulations contain from about 1% w/w to about 10% w/w water. In another preferred embodiment, the formulations contain about 11% w/w, about 12% w/w, about 14% w/w, about 26% w/w or about 31% w/w water.

In yet another embodiment, the formulations contain from about 10% w/w to about 60% w/w ethanol. In a preferred embodiment, the formulations contain from about 20% w/w to about 50% w/w ethanol. In another preferred embodiment, the formulations contain from about 35% w/w to about 55% w/w ethanol. In another preferred embodiment, the formulations contain about 37% w/w, about 38% w/w, about 39% w/w, about 40% w/w, about 45% w/w or about 50% w/w ethanol. In a more preferred embodiment, the formulation contains about 50% w/w ethanol.

In an embodiment, the formulations contain from about 5% w/w to about 50% w/w glycerol. In a preferred embodiment, the formulations contain from about 10% w/w to about 40% w/w glycerol. In a more preferred embodiment, the formulations contain from about 5% w/w to about 30% w/w glycerol. In another preferred embodiment, the formulations contain about 5% w/w, about 10% w/w, about 12.5% w/w, about 15% w/w, about 20% w/w, about 25% w/w, about 27% w/w, about 28% w/w, about 29% w/w, about 30% w/w, about 32% w/w and about 35% w/w glycerol. In a more preferred embodiment, the formulation contains about 10% w/w glycerin.

In a further embodiment, the formulations contain from about 0.1% w/w to about 50% w/w propylene glycol. In a more preferred embodiment, the formulations contain from about 0.1% w/w to about 40% w/w propylene glycol. In another preferred embodiment, the formulations contain from about 5% w/w to about 30% w/w propylene glycol. In another embodiment, the formulation contains about 5% w/w, about 10% w/w, about 12.5% w/w, about 15% w/w about 20% w/w, about 25% w/w, about 27% w/w, about 28% w/w, about 29% w/w, about 30% w/w, about 32% w/w and about 35% w/w propylene glycol.

In another embodiment, the formulations contain from about 0.1% w/w to about 50% w/w polyethylene glycol 400. In a more preferred embodiment, the formulations contain from about 10% w/w to about 40% w/w polyethylene glycol 400.

Preferably, the formulations of the present invention are propellant free.

In another embodiment, the formulations of the present invention contain sildenafil in the form of a base or an acid.

In another embodiment, the formulations contain a pharmaceutically acceptable salt of sildenafil. In a preferred embodiment, the formulations contain a salt selected from the group consisting of citrate, hydrochloride, halide, sulfate, phosphate, acetate, maleate, succinate, ascorbate, carbonate, mesylate and lactate. One of skill in the art could use other pharmaceutically acceptable sildenafil salts in the formulations of the present invention.

In a further embodiment, the formulation contains an antioxidant and/or stabilizer, a permeation enhancer, a sweetener, a sweetness enhancer, a pH modifier, a flavoring agent, a preservative, or a combination thereof.

In a preferred embodiment, the formulations may contain an antioxidant and/or stabilizer. In a more preferred embodiment, the antioxidant and/or stabilizer is selected from the group consisting of ascorbyl palmitate, ascorbic acid, dl-alpha tocopherol, butylated hydroxytoluene, butylated hydroxyanisole, cysteine HCl, citric acid, ethylenediamine tetra acetic acid (EDTA), methionine, citric acid, sodium citrate, sodium ascorbate, sodium thiosulfate, sodium metabisulfite, sodium bisulfite, propyl gallate, glutathione and thioglycerol. Other appropriate antioxidants known by those of skill in the art could also be added to formulations of the present invention. In a preferred embodiment, the formulations contain from about 0.001% w/w to about 1% w/w of the antioxidant. In a more preferred embodiment, the formulations may contain from about 0.005% w/w to about 0.05% w/w of the antioxidant. In a further preferred embodiment, the formulation does not contain an anti-oxidant.

In another embodiment, the formulation contains a permeation enhancer. In a preferred embodiment, the permeation enhancer is selected from the group consisting of menthol, limonene, carvone, methyl chitosan, polysorbates including Tween® 80 (polysorbate 80; Tween is a registered trademark of Uniqema Americas, LLC), sodium lauryl sulfate, glyceryl oleate, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylenic acid, lauric acid, myristic acid, palmitic acid, oleic acid, stearic acid, linolenic acid, arachidonic acid, benzethonium chloride, benzethonium bromide, benzalkonium chloride (“BKC”), cetylpyridium chloride, edetate disodium dihydrate, sodium desoxycholate, sodium deoxyglycolate, sodium glycocholate, sodium caprate, sodium taurocholate, sodium hydroxybenzoyl amino caprylate, dodecyl dimethyl aminopropionate, L-lysine, glycerol oleate, glyceryl monostearate, citric acid, peppermint oil and a combination thereof. In a preferred embodiment the permeation enhancer is selected from the group consisting of menthol, a medium chain glyceride or a medium chain fatty acid such as caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylenic acid or lauric acid, BKC and a combination thereof. In a more preferred embodiment the medium chain fatty acid is caprylic acid or capric acid, preferably caprylic acid. In a further preferred embodiment, the formulation does not contain a permeation enhancer.

In a preferred embodiment, the formulations contain from about 0.1% w/w to about 20% w/w of caprylic acid.

In another preferred embodiment, the formulations contain from about 0.1% w/w to about 10% w/w of caprylic acid.

In another preferred embodiment, the formulations contain from about 0.1% w/w to about 5% w/w of caprylic acid.

In a preferred embodiment, the formulations contain from about 0.1% to about 5 w/w of L-menthol.

In another preferred embodiment, the formulations contain from about 0.1% w/w to about 3% w/w of L-menthol.

In another preferred embodiment, the formulations contain from about 0.1% w/w to about 1% w/w of L-menthol.

In a preferred embodiment, the permeation enhancer is selected from the group consisting of menthol in an amount from about 0.01% to about 10% w/w, caprylic acid in an amount from about 0.1% to 10% w/w, BKC in an amount from about 0.001% to 10% w/w and a combination thereof.

In another preferred embodiment, the permeation enhancer is selected from the group consisting of about 0.01% to 1% w/w menthol, about 0.1% to 10% w/w caprylic acid, about 0.001 to 0.2% w/w BKC, about 0.01 to 1% w/w cetylpyridinium chloride and a combination thereof.

In a preferred embodiment, the formulations contain from about 0.1% to about 5% w/w of L-menthol, and from about 0.1 to 10% caprylic acid

In another preferred embodiment, the formulations contain from about 0.1% w/w to about 2% w/w of L-menthol, and from about 2 to 10% caprylic acid

In another preferred embodiment, the permeation enhancer is 0.5% w/w menthol and 2% w/w caprylic acid. In a more preferred embodiment, the formulation contains about 0.5% w/w menthol, and 3.68% w/w caprylic acid.

In another preferred embodiment, the permeation enhancer is 0.5% w/w menthol 0.01% w/w BKC and 2% w/w caprylic acid.

In another preferred embodiment, the permeation enhancer is 0.5% w/w menthol 0.1% w/w cetylpyridinium chloride and 2% w/w caprylic acid. In another preferred embodiment, the formulations may contain only menthol as the permeation enhancer without any caprylic acid.

In a preferred embodiment, the formulations contain a sweetener. In a more preferred embodiment, the sweetener is selected from the group consisting of sucralose, aspartame, saccharin, dextrose, mannitol, glycerin, mannitol and xylitol. In another preferred embodiment, the sweetener is from about 0.1 w/w to about 5% w/w sucralose.

In a further embodiment, the formulation may contain a sweetness enhancer, an ammonium salt form of crude and refined Glycyrrhizic Acid, for example, Magnasweet® product (available from Mafco Worldwide Corporation, Magnasweet is a registered trademark of Mafco Worldwide Corporation). Magnasweet® products use the ammonium salt forms of crude and refined Glycyrrhizic Acid. Glycyrrhizic Acid is also available as a pure derivative in the sodium and potassium salt forms.

In another embodiment, the formulations contain a pH modifier. In a preferred embodiment, the pH modifier adjusts the pH of the formulation to from about 2 and about 6. In a more preferred embodiment, the pH modifier adjusts the pH of the formulation to from about 2 and about 5. In a more preferred embodiment, the pH modifier adjusts the pH of the formulation to about 3, 3.6, 4, 4.25 and 4.5±0.2. In another most preferred embodiment, the pH is about 3.6 or 4.5±0.2.

In another embodiment, the formulations contain a flavoring agent. In a preferred embodiment, the formulations contain a flavoring agent selected from the group consisting of peppermint oil, menthol, spearmint oil, citrus oil, cinnamon oil, strawberry flavor, cherry flavor, raspberry flavor, orange oil, and a combination thereof. Other appropriate flavoring agents known by those of skill in art could also be added to formulations of the present invention. In a preferred embodiment, the formulations contain from about 0.001% w/w to about 1% w/w of the flavoring agent. In a more preferred embodiment, the formulations contain from about 0.005% w/w to about 0.5% w/w of the flavoring agent.

In yet another embodiment, the formulations may contain a preservative. In a preferred embodiment, the preservative is selected from the group consisting of butyl paraben, methyl paraben, ethyl paraben, propyl paraben, sodium benzoate, benzyl alcohol, sorbic acid and benzoic acid. In a preferred embodiment, the formulations contain from about 0.001% w/w to about 1% w/w of the preservative. In a more preferred embodiment, the formulations contain from about 0.005% w/w to about 0.05% w/w of the preservative. In another preferred embodiment, the formulation does not contain a preservative.

In a further embodiment, the present invention is directed to propellant free sublingual spray formulations comprising from about 5% w/w to about 20% w/w sildenafil or a salt thereof, from about 35% w/w to about 55% w/w ethanol, from about 1% w/w to about 30% w/w water, an excipient selected from the group consisting of about 5% w/w to about 35% w/w glycerol and from about 5% to about 30% propylene glycol, and from about 0.1% w/w to about 60% w/w diluted hydrochloric acid and optionally a permeation enhancer selected from menthol, caprylic acid, benzalkonium chloride, cetylpyridinium chloride and a combination thereof.

In another aspect, the present invention is directed to a propellant free sublingual spray formulation comprising about 8% w/w sildenafil or a salt thereof, about 40% w/w ethanol, about 10% w/w glycerol, about 26% w/w water, about 12% w/w diluted hydrochloric acid, and a permeation enhancer comprising 0.5% w/w menthol and 2% w/w caprylic acid.

In another aspect, the present invention is directed to a propellant free sublingual spray formulation comprising about 8% w/w sildenafil or a salt thereof, about 50% w/w ethanol, about 15% w/w glycerol, about 12% w/w water, about 12% w/w diluted hydrochloric acid, and a permeation enhancer comprising 0.5% w/w menthol, 0.1% cetylpyridinium chloride and 2% w/w caprylic acid.

In another aspect, the present invention is directed to a propellant free sublingual spray formulation comprising about 8% w/w sildenafil or a salt thereof, about 50% w/w ethanol, about 15% w/w propylene glycol, about 12% w/w water, about 12% w/w diluted hydrochloric acid, and a permeation enhancer comprising 0.5% w/w menthol, 0.1% cetylpyridinium chloride and 2% w/w caprylic acid.

In another aspect, the present invention is directed to a propellant free sublingual spray formulation comprising from about 16% w/w sildenafil or a salt thereof, from about 50% w/w ethanol, from about 6% w/w water, an excipient selected from the group consisting of from about 10% w/w glycerol or propylene glycol or a combination thereof, from about 0.5% L-menthol, from about 3.68% Caprylic acid, or without any Caprylic acid, from about 0.15% flavoring agent, from about 0.4% sweetener and from about 12% w/w hydrochloric acid (Normality is 3N) with the pH from about 3.6, 4, 4.25 or 4.5, preferably 3.6 or 4.5.

In another aspect, the present invention is directed to a propellant free sublingual spray formulation comprising:

-   -   about 9% w/w sildenafil or a salt thereof;     -   about 50% w/w ethanol;     -   about 10% w/w glycerol;     -   about 1% w/w sucralose     -   about 0.15% w/w of a flavoring agent;     -   about 14% w/w water;     -   about 13% w/w diluted hydrochloric acid (1.5 N); and     -   a permeation enhancer comprising 0.5% w/w menthol or 2% w/w         caprylic acid, or combination thereof,     -   wherein the formulation has a pH from about 3 to about 5.

In another aspect, the present invention is directed to a propellant free sublingual spray formulation comprising:

-   -   about 17% w/w sildenafil or a salt thereof     -   about 50 w/w ethanol;     -   about 10% w/w glycerol;     -   about 0.4% w/w sucralose     -   about 0.15% w/w of a flavoring agent;     -   about 6% w/w water;     -   about 12% w/w diluted hydrochloric acid (3N); and     -   a permeation enhancer comprising 0.5% w/w menthol or 4% w/w         caprylic acid, or combination thereof,         wherein the formulation has a pH from about 3 to about 5.

In another aspect, the present invention is directed to a propellant free sublingual spray formulation comprising:

-   -   about 17% w/w sildenafil or a salt thereof     -   about 50 w/w ethanol;     -   about 10% w/w glycerol;     -   about 0.4% w/w sucralose;     -   about 0.15 w/w flavor;     -   about 10% w/w water;     -   about 12% w/w diluted hydrochloric acid (3N); and     -   a permeation enhancer comprising 0.5% w/w menthol,     -   wherein the formulation has a pH from about 3 to about 5.

In an alternative embodiment, the present invention is directed to methods for treating sexual dysfunction in men comprising administering formulations of the present invention to a patient in need thereof.

In a preferred embodiment, the formulations of the present invention are delivered via a spray pump to treat sexual dysfunction. In a more preferred embodiment, the spray pumps deliver from about 50 to about 400 μL to the patient. In a most preferred embodiment, the formulations are delivered under the patient's tongue.

In another embodiment, the present invention is directed to methods for treating pulmonary arterial hypertension in a human comprising administering the formulation of claim 1 to a patient in need thereof.

In a preferred embodiment, the formulations of the present invention are delivered via a spray pump to treat arterial hypertension. In a more preferred embodiment, the spray pumps deliver from about 50 to about 400 μL to the patient. In a most preferred embodiment, the formulations are delivered under the patient's tongue.

In another embodiment, the invention is directed to methods for treating sexual dysfunction in men comprising administering formulations of the present invention to a patient in need of such treatment.

In yet another embodiment, the invention is directed to methods for treating pulmonary arterial hypertension in humans comprising administering formulations of the present invention to a patient in need of such treatment.

In a preferred embodiment, the formulations of the present invention do not discolor when stored at 40° C. or 55° C.

In yet another embodiment, the formulations of the present invention are capable of producing a droplet size distribution wherein the mean Dv(10) is from about 18 to about 35 microns during administration.

In a further embodiment, the formulations of the present invention are capable of producing a droplet size distribution wherein the mean Dv(50) is from about 40 to about 75 microns during administration.

In yet another embodiment, the formulations of the present invention are capable of producing a droplet size distribution wherein the mean Dv(90) is from about 50 to about 550 microns during administration. Preferably, the formulations of the present invention are capable of producing a droplet size distribution wherein the mean Dv(90) is from about 80 to about 550 microns during administration.

In yet another embodiment, the formulations of the present invention are capable of producing a spray span ((Dv90−Dv10)/Dv50) of from about 0.1 to about 10. Preferably, the formulations of the present invention are capable of producing a spray span ((Dv90−Dv10)/Dv50) of from about 1 to about 8.

As used herein, “sildenafil” refers to the base or a pharmaceutically acceptable salt, ester, derivative, or prodrug thereof.

As used herein, “propellant free” refers to a formulation that is not administered using compressed gas.

As used herein, “male sexual dysfunction” refers to erectile dysfunction or impotence. Erectile dysfunction and impotence are characterized by the inability to develop or maintain an erection of the penis during sexual activities.

As used herein, “pulmonary arterial hypertension” refers to the condition of having abnormally high blood pressure in the lungs.

As used herein, all numerical values relating to amounts, weights, and the like, that are defined as “about” each particular value is plus or minus 10%. For example, the phrase “about 10% w/w” is to be understood as “9% w/w to 11% w/w.” Therefore, amounts within 10% of the claimed value are encompassed by the scope of the claims.

As used herein “% w/w” and “percent w/w” refer to the percent weight of the total formulation.

As used herein the term “effective amount” refers to the amount necessary to treat a patient in need thereof.

As used herein the term “patient” refers, but is not limited to, a person that is being treated for male sexual dysfunction or pulmonary arterial hypertension.

As used herein the term “pharmaceutically acceptable” refers to ingredients that are not biologically or otherwise undesirable in a sublingual dosage form.

As used herein the term “a combination thereof” includes two or more ingredients.

The disclosed embodiments are simply exemplary embodiments of the inventive concepts disclosed herein and should not be considered as limiting, unless the claims expressly state otherwise.

The following examples are intended to illustrate the present invention and to teach one of ordinary skill in the art how to use the formulations of the invention. They are not intended to be limiting in any way.

EXAMPLES Example 1

Preparation of a Sildenafil Sublingual Formulation

In order to prepare a sildenafil sublingual formulation, the components as indicated in “Table 1. The Components of Formulation 1” below were weighed. The components were mixed until a clear solution was formed.

Sildenafil base U.S.P. (available from Pol Pharma) was used as the source of sildenafil in the formulations that follow. Ethanol, 200 Proof, denatured, U.S.P., (available from Spectrum) was used as the source of alcohol. Strawberry flavor, Nat&Art 915.0543 U, (available from FONA) was used as the source of flavoring. L-menthol, crystal, U.S.P., was also used as the source of flavoring. Sucralose, N.F., (available from Spectrum) was used as the source of sweetener. Glycerol, U.S.P., 99.0-100.5%, (available from EMD Milipore) was used as solvent and nucleation inhibitor. Water, U.S.P., purified, (available from RICCA) was used as the source of solvent. 3N HCL, U.S.P. (Prepared from J. T baker 6N) was used as the source of acid.

TABLE 1 The Components of Formulation 1 % w/w Sildenafil base 15.8 Ethanol 40 Flavoring agent 0.15 L-menthol 0.05 Sucralose 0.8 Glycerol 28 Water 3.5 3N HCL 11.8 pH adjusted to 4.5 with 3.0N NaOH 100

Example 2

Preparation of Additional Sildenafil Sublingual Formulations

In order to prepare a sildenafil sublingual formulation, the components as indicated in “Table 2. The Components of Formulations 2A to 2K” below were weighed. The components were mixed until a clear solution was formed.

Sildenafil base U.S.P. (available from Pol Pharma) was used as the source of sildenafil in the formulations that follow. Ethanol, 200 Proof, denatured, U.S.P., (available from Spectrum) was used as the source of alcohol. Strawberry flavor, Nat&Art 915.0543 U, (available from FONA) was used as the source of flavoring. L-menthol, crystal, U.S.P., was also used as the source of flavoring. Sucralose, N.F., (available from Spectrum) was used as the source of sweetener. Glycerol, U.S.P., 99.0-100.5%, (available from EMD Milipore) was used as the source of solvent. Water, U.S.P., purified, (available from RICCA) was used as the source of another solvent. 3N HCL, U.S.P. (available from J. T. Baker) was used as the source of acid.

TABLE 2 The Components of Formulation 2A to 2K % w/w 2A 2B 2C 2D 2E 2F 2G 2H 2I 2J 2K Sildenafil base 16 16 16 16 16 16 16 16 16 16 15.8 Ethanol 40 39 37.5 37.5 36.8 39 39 40 40 38 40 Flavoring — — — — — 0.15 0.15 — — 0.15 0.15 L-menthol — — — — — — — — — — 0.5 Sucralose — — — — — 0.8 0.8 — — 0.8 0.8 Ammonium salt — — — — — 0.05 0.05 — — 0.05 — form of crude and refined Glycyrrhizic Acid Polyvinylpyrrolidone — — — — — — 0.5 — 1 — — Glycerol 25 30 30 32.2 34.7 28.7 28.2 27.5 27 30 28 Water 7.5 5 5 2.8 1 3.8 3.8 4.5 4.5 3.5 3.47 3N HCL (Diluted 11.5 11.5 11.5 11.5 11.5 11.5 11.5 11.5 11.5 11.5 11.75 from 6N HCL)

Example 3

Preparation of Additional Sildenafil Sublingual Formulations

TABLE 3 The Components of Formulations 3A and 3B % w/w 3A 3B Sildenafil base 20 20 Ethanol 44.5 40 Glycerol 20 25 Water 1 1 3N HCL 14.5 14

Example 4

Preparation of Additional Sildenafil Sublingual Formulations

TABLE 4 The Components of Formulations 4A through 4L % w/w 4A 4B 4C 4D 4E 4F 4G 4H 4I 4J 4K 4L Sildenafil base 16.56 16.56 16.56 8.28 8.28 8.28 8.28 16.56 8.28 8.28 8.28 8.28 Ethanol 40 40 22.5 40 40 40 40 40 50 50 50 50 Malic Acid — — 30 — — — — — — — — — Flavoring 0.15 0.15 — 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 L-menthol 0.05 0.05 — 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Cetylpyridinium — — — — — — — — 0.1 0.1 0.1 0.1 chloride Sucralose 0.8 0.8 — 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Propylene 28 — — — 5 — 10 — — — 15 12.5 glycol Glycerol — 28 — 5 — 10 — 25 15 12.5 — — Water 2.11 2.11 30.94 30.94 30.94 25.94 25.94 2.66 11.42 13.92 11.42 13.92 Caprylic Acid — — — 2 2 2 2 2 2 2 2 2 1.5N HCl — — — — — 12.33 12.33 — 11.75 11.75 11.75 11.75 3N HCl 12.33 12.33 — 12.33 12.33 — — 12.33 — — — — pH 4.5 ± 4.5 ± 2.45 4.5 ± 0.1 4.5 ± 0.1 4.5 ± 0.1 4.5 ± 0.1 4.5 ± 0.1 3.0 ± 0.2 3.0 ± 0.2 3.0 ± 0.2 3.0 ± 0.2 0.1 0.1

Sildenafil base U.S.P. (available from Pol Pharma) was used as the source of sildenafil in the formulations that follow. Strawberry flavor, Nat&Art 915.0543 U, (available from FONA) was used as the source of flavoring. L-menthol, crystal, U.S.P., was also used as the source of flavoring. Sucralose, N.F., (available from Spectrum) was used as the source of sweetener. Glycerol, U.S.P., 99.0-100.5%, (available from EMD Milipore) was used as the source of solvent. Water, U.S.P., purified, (available from RICCA) was used as the source of another solvent. 1.5 N HCl or 3N HCl, U.S.P. (available from J. T. Baker) was used as the source of acid.

Example 5

Preparation of Additional Sildenafil Sublingual Formulations

TABLE 5 The Components of Formulations 5A through 5N % w/w 5A 5B 5C 5D 5E 5F 5G 5H 5I 5J 5K 5L 5M 5N Sildenafil 16.84 16.84 16.84 16.84 16.84 16.84 16.84 15.80 15.80 14.76 14.76 9.13 20 25 base Ethanol 50 50 50 50 50 45 45 50 50 50 50 50 48 40 Flavoring 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 L- 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 menthol Sucralose 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.8 0.8 0.8 Glycerol 10 10 10 10 10 15 15 10 10 10 10 10 10 10 Water 6.24 6.24 9.92 6.24 6.24 6.24 6.24 8.24 8.24 10.26 10.26 14.18 12 14.24 Caprylic 3.68 3.68 — 3.68 3.68 3.68 3.68 3.46 3.46 3.23 3.23 2 — — Acid 3N HCl 12.19 12.19 12.19 12.19 12.19 12.19 12.19 11.44 11.44 10.68 10.68 13.22 — — 6N HCl — — — — — — — — — — — — 8.55 9.31 pH 4.5 ± 3.6 ± 3.6 ± 4.0 ± 4.25 ± 3.6 ± 4.5 ± 3.6 ± 0.1 4.5 ± 0.1 3.6 ± 0.1 4.5 ± 0.1 3.6 ± 0.1 4.5 ± 0.1 4.5 ± 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1

Sildenafil Base U.S.P (available from Pol Pharma) was used as the source of sildenafil in the formulations that follow. Strawberry flavor, Nat & Art 915.0543 U, (available from FONA) was used as the source of flavoring. L-menthol, crystal, U.S.P., was also used as the source of flavoring. Sucralose N.F., (available from Spectrum) was used as the source of sweetener. Glycerol, U.S.P., 99.0-100.5%, (available from EMD Millipore) was used as the source of solvent. Water, U.S.P., purified, (available from RICCA) was used as the source of another solvent. 1.5 N HCl or 3 N HCl, U.S.P., (available from J. T. Baker) was used as the source of acid.

Example 6

Sildenafil Stability Testing

In order to determine the stability of Formulations 3A and 3B the formulations were subjected to standard stability testing to determine sildenafil concentrations after being subject to harsh storage conditions. The results are below in Table 6.

TABLE 6 Sildenafil Stability in Formulations 3A and 3B Label % of % of % of Claim Conc Initial Conc Initial Conc Initial Formulation # (mg/mL) (mg/mL) Conc (mg/mL) Conc (mg/mL) Conc T0 1 Week 2 Weeks 3A 200.4  5° C. 199.18 100.00% 197.56 99.20% 25° C. 199.04 99.90% 40° C. 199.13 100.00% 199.72 100.30% 55° C. 199.85 100.30% 3B 202.8  5° C. 202.86 100.00% 201.91 99.50% 25° C. 203.36 100.20% 40° C. 202.69 99.90% 205.28 101.20% 55° C. 202.72 99.90% 4 Weeks 6 Weeks 8 Week 3A 200.4  5° C. 25° C. 40° C. 201.02 100.90% 200.13 100.50% 200.79 100.80% 55° C. 201.76 101.30% 203.18 102.00% 201.91 101.40% 3B 202.8  5° C. 25° C. 40° C. 204.11 100.60% 204.86 101.00% 200.89 99.00% 55° C. 201.55 99.40% 204.09 100.60% 204.93 101.00%

As can be seen in Table 6 Formulations 3A and 3B maintained at least 99% of initial sildenafil concentrations at 40 and 55° C. as determined by chemical analysis.

Example 7

Impurity Formation

In order to further determine the stability of Formulations 1, 3A, 3B, 5A, 5B, 5C, 5D and 5E, the formulations were subjected to standard stability testing to determine impurity levels. The results are below in Tables 7-11.

TABLE 7 Stability of Formulation 1 at 55° C. Stability at 55° C. Formulation # 1 RRT Specifications T0 2 Week 3 Week 4 Week 6 Week 8 Week Clarity clear clear clear clear clear clear clear Color colorless colorless colorless colorless colorless colorless colorless pH 4.511 4.577 4.548 4.747 4.531 4.634 Assay (%) 95-105%  98.90% 98.90% 99.90% 99.80% 99.80% 99.70% Impurity A 1.15 <0.15% BQL BQL BQL BQL BQL BQL Impurity B 0.65 <0.15% ND BQL BQL BQL BQL 0.05% Impurity C 0.58 <0.15% ND ND ND BQL BQL BQL Impurity D 0.25 <0.15% BQL BQL BQL BQL BQL BQL Unknown 0.41 <0.10% BQL BQL BQL BQL BQL BQL Impurities 0.52 <0.10% BQL BQL BQL BQL BQL BQL 0.62 <0.10% BQL BQL BQL BQL BQL BQL 0.7 <0.10% BQL BQL BQL BQL BQL BQL 0.8 <0.10% BQL BQL BQL BQL BQL BQL 1.06 <0.10% ND ND ND ND BQL ND Total Impurity <0.50% 0.00% 0.00% 0.00% 0.00% 0.00% 0.05% NP = Not Performed, ND = Not Detected (Limit of Detection = 0.01%) BQL = Below Quantification Limit (Limit of Quantification = 0.05%), RRT = Relative Retention Time

TABLE 8 Impurity Formation in Formulations 3A and 3B at 40 Degrees Celsius Drug RRT Specification Substance t = 0 1 week 2 weeks 4 weeks 6 weeks 8 weeks FORMULATION # 3A, 40° C./75% RH Physical clear, clear, clear, clear, clear, clear, clear, appearance colorless colorless colorless colorless colorless colorless colorless Assay (% 95.0-105.0% 100.70% 99.60% 99.40% 99.70% 100.90% 100.50% 100.00% of initial Conc) Impurity A 1.16 <0.15% BQL BQL BQL BQL BQL BQL BQL Impurity B 0.64 <0.15% ND BQL ND BQL ND BQL BQL Impurity C 0.57 <0.15% BQL ND ND ND ND BQL ND Impurity D 0.25 <0.15% BQL BQL BQL BQL BQL BQL BQL Unknown 0.24 <0.10% ND ND ND ND ND ND ND Impurity RRT 0.24 Unknown 0.61 <0.10% ND BQL BQL BQL BQL BQL BQL Impurity RRT 0.61 Total <0.50% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% Impurities: FORMULATION # 3B, 40° C./75% RH Physical clear, clear, clear, clear, clear, clear, clear, appearance colorless colorless colorless colorless colorless colorless colorless Assay (% 95.0-105.0% 100.70% 101.40% 99.90% 101.20% 101.30% 101.00% 99.10% of initial Conc) Impurity A 1.16 <0.15% BQL BQL BQL BQL BQL BQL BQL Impurity B 0.64 <0.15% ND BQL ND BQL BQL BQL BQL Impurity C 0.57 <0.15% BQL ND ND ND ND ND ND Impurity D 0.25 <0.15% BQL BQL BQL BQL BQL BQL BQL Unknown 0.24 <0.10% ND ND ND ND ND ND ND Impurity RRT 0.24 Unknown 0.61 <0.10% ND BQL BQL BQL BQL BQL BQL Impurity RRT 0.61 Total <0.50% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% Impurities: NP = Not Performed, ND = Not Detected (Limit of Detection = 0.01%) BQL = Below Quantification Limit (Limit of Quantification = 0.05%), RRT = Relative Retention Time

TABLE 9 Impurity Formation in Formulations 3A and 3B at 55 Degrees Celsius Drug RRT Specification Substance t = 0 2 weeks 4 weeks 6 weeks 8 weeks FORMULATION # 3A, 55° C. Physical clear, clear, clear, clear, clear, clear, appearance colorless colorless colorless colorless colorless colorless Assay (% of 95.0-105.0% 100.70% 99.60% 99.70% 100.60% 102.00% 100.80% initial Conc) Impurity A 1.16 <0.15% BQL BQL BQL BQL BQL BQL Impurity B 0.64 <0.15% ND BQL BQL BQL BQL BQL Impurity C 0.57 <0.15% BQL ND ND BQL ND BQL Impurity D 0.25 <0.15% BQL BQL BQL BQL BQL BQL Unknown 0.24 <0.10% ND ND ND ND ND ND Impurity RRT 0.24 Unknown 0.61 <0.10% ND BQL BQL BQL BQL BQL Impurity RRT 0.61 Total <0.50% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% Impurities: FORMULATION # 3B, 55° C. Physical clear, clear, clear, clear, clear, clear, appearance colorless colorless colorless colorless colorless colorless Assay (% of 95.0-105.0% 100.70% 101.40% 100.00% 99.40% 100.60% 101.00% initial Conc) Impurity A 1.16 <0.15% BQL BQL BQL BQL BQL BQL Impurity B 0.64 <0.15% ND BQL BQL BQL BQL BQL Impurity C 0.57 <0.15% BQL ND ND BQL BQL BQL Impurity D 0.25 <0.15% BQL BQL BQL BQL BQL BQL Unknown 0.24 <0.10% ND ND ND ND ND ND Impurity RRT 0.24 Unknown 0.61 <0.10% ND BQL BQL BQL BQL BQL Impurity RRT 0.61 Total <0.50% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% Impurities: NP = Not Performed, ND = Not Detected (Limit of Detection = 0.01%) BQL = Below Quantification Limit (Limit of Quantification = 0.05%), RRT = Relative Retention Time

TABLE 10 Stability of Formulations 5A and 5B at 40 Degrees Celsius Stability @ 40° C. 5A RRT T0 4 Week Clarity clear clear Color colorless colorless pH 4.5    4.527 Assay (%) 98.70% 101.30% Impurity A 1.77 BQL BQL Impurity B — ND BQL Impurity C — ND ND Impurity D 0.59 BQL BQL Unknown 0.33 BQL BQL Impurities 0.39 ND BQL 0.61 ND BQL 0.68 ND BQL 1.25 ND BQL Total Impurity  0.00%  0.00% Stability @ 40° C. 5B RRT T0 4 Week Clarity clear clear Color colorless colorless pH 3.6    3.612 Assay (%) 99.30% 103.80% Impurity A 1.77 BQL BQL Impurity B — ND BQL Impurity C — ND ND Impurity D 0.59 BQL BQL Unknown 0.33 BQL BQL Impurities 0.39 ND BQL 0.61 ND BQL 0.68 ND BQL 1.25 ND BQL Total Impurity  0.00%  0.00% NP = Not Performed, ND = Not Detected (Limit of Detection = 0.01%) BQL = Below Quantification Limit (Limit of Quantification = 0.05%), RRT = Relative Retention Time

TABLE 11 Stability of Formulations 5A and 5B at 25 Degrees Celsius Stability @ 25° C. 5A RRT T0 4 Week Clarity clear clear Color colorless colorless pH 4.5    4.411 Assay (%) 98.70% 101.40% Impurity A 1.77 BQL BQL Impurity B — ND BQL Impurity C — ND ND Impurity D 0.59 BQL BQL Unknown 0.33 BQL BQL Impurities 0.39 ND BQL 0.61 ND BQL 0.68 ND BQL 1.25 ND BQL Total Impurity  0.00%  0.00% Stability @ 25° C. 5B RRT T0 4 Week Clarity clear clear Color colorless colorless pH 3.6    3.656 Assay (%) 99.30% 100.70% Impurity A 1.77 BQL BQL Impurity B — ND BQL Impurity C — ND ND Impurity D 0.59 BQL BQL Unknown 0.33 BQL BQL Impurities 0.39 ND BQL 0.61 ND BQL 0.68 ND BQL 1.25 ND BQL Total Impurity  0.00%  0.00% NP = Not Performed, ND = Not Detected (Limit of Detection = 0.01%) BQL = Below Quantification Limit (Limit of Quantification = 0.05%), RRT = Relative Retention Time

TABLE 12 Stability of Formulations 5A, 5B, 5C, 5D, 5E at 55 Degrees Celsius Stability @ 55° C. 5A RRT T0 2 Week 4 Week Clarity clear clear clear Color colorless colorless colorless pH 4.5 4.31 4.496 Assay (%) 98.70% 99.60% 102.40% Impurity A 1.77 BQL ND BQL Impurity B — ND ND BQL Impurity C — ND ND BQL Impurity D 0.59 BQL BQL BQL Unknown 0.33 BQL BQL BQL Impurities 0.39 ND BQL BQL 0.61 ND BQL BQL 0.68 ND BQL BQL 1.25 ND BQL BQL Total 0.00% 0.00% 0.00% Impurity Stability @ 55° C. 5B RRT T0 2 Week 4 Week Clarity clear clear clear Color colorless colorless colorless pH 3.6 3.602 3.693 Assay (%) 99.30% 100.90% 100.40% Impurity A 1.77 BQL ND BQL Impurity B — ND ND BQL Impurity C — ND ND BQL Impurity D 0.59 BQL BQL BQL Unknown 0.33 BQL BQL BQL Impurities 0.39 ND BQL BQL 0.61 ND BQL BQL 0.68 ND BQL BQL 1.25 ND BQL BQL Total 0.00% 0.00% 0.00% Impurity Stability @ 55° C. 5C RRT T0 2 Week Clarity clear clear Color colorless colorless pH 3.6 3.632 Assay (%) 101.20% 101.60% Impurity A — ND BQL Impurity B — ND BQL Impurity C — ND ND Impurity D 0.59 BQL BQL Unknown 0.32 BQL BQL Impurities 0.39 BQL BQL 0.61 BQL BQL 0.68 BQL BQL Total 0.00% 0.00% Impurity Stability @ 55° C. 5D RRT T0 2 Week Clarity clear clear Color colorless colorless pH 4 4.049 Assay (%) 100.10% 100.20% Impurity A — ND BQL Impurity B — ND BQL Impurity C — ND ND Impurity D 0.59 BQL BQL Unknown 0.32 BQL BQL Impurities 0.39 BQL BQL 0.61 BQL BQL 1.25 BQL BQL Total 0.00% 0.00% Impurity Stability @ 55° C. 5E RRT T0 2 Week Clarity clear clear Color colorless colorless pH 4.25 4.246 Assay (%) 100.10% 99.70% Impurity A — ND BQL Impurity B — ND BQL Impurity C — ND ND Impurity D 0.59 BQL BQL Unknown 0.32 BQL BQL Impurities 0.39 BQL BQL 0.61 BQL BQL 0.68 BQL BQL Total 0.00% 0.00% Impurity NP = Not Performed, ND = Not Detected (Limit of Detection = 0.01%) BQL = Below Quantification Limit (Limit of Quantification = 0.05%), RRT = Relative Retention Time

As can be seen in Tables 7-12 the formulations were observed to be clear and colorless. Surprisingly, the formulations also had undetectable levels of impurities as determined by chemical analysis except for Formulation 1, which had only 0.05% total impurities after 8 weeks at 55° C.

Example 8

Freeze/Thaw Stability

In order to further determine the stability of Formulations 1, 2A to 2I, 3A and 3B, 4A to 4E and 5A to 5E, the formulations were subjected to standard low temperature and freeze/thaw stability testing. The results are below in Tables 13-18.

TABLE 13 Stability of Formulation 1 to Freeze/Thaw Testing Formulation Drug Cycle 1 Cycle 1 Cycle 2 Cycle 2 Cycle 3 Cycle 3 # 1 Substance −20° C. 25° C. −20° C. 25° C. −20° C. 25° C. Day 0 2 4 6 8 10 12 Physical clear clear clear clear clear clear clear clear appearance Color colorless colorless colorless colorless colorless colorless colorless colorless

TABLE 14 Stability of Formulations 2A to 2I to 22 Degrees Celsius and Freeze/Thaw Studies Cycle 1 Cycle 2 Cycle 3 Freeze-Thaw Freeze-Thaw Freeze-Thaw Physical Observation Cycle Cycle Cycle Room Temp Freeze Thaw Freeze Thaw Freeze Thaw # Time (22° C.) 5° C. −20° C. (−20° C.) (22° C.) (−20° C.) (22° C.) (−20° C.) (22° C.) 2A 2 Clear Clear Crystal clear clear clear clear clear clear Months growth (After 10 days) 2B 2 Clear Clear Crystal clear clear clear clear clear clear Months growth (After 10 days) 2C 2 Clear Clear Crystal clear clear clear clear clear clear Months growth (After 7 days) 2D 2 Clear Clear Crystal clear clear clear clear clear clear Months growth (After 7 days) 2E 2 Clear Clear Crystal clear clear clear clear clear clear Months growth (After 14 days) 2F 2 Clear Clear Crystal clear clear clear clear clear clear Months growth (After 14 days) 2G 2 Clear Clear Crystal clear clear clear clear clear clear Months growth (After 14 days) 2H 2 Clear Clear Crystal clear clear clear clear clear clear Months growth (After 14 days) 2I 2 Clear Clear Crystal clear clear clear clear clear clear Months growth (After 16 days)

TABLE 15 Stability of Formulations 3A and 3B to Freeze/Thaw Testing Drug Cycle 1, Cycle 1, Cycle 2, Cycle 2, Cycle 3, Cycle 3, Substance t = 0 −20° C. 25° C. −20° C. 25° C. −20° C. 25° C. Formulation # 3A Date Nov. 26, 2014 Dec. 1, 2014 Dec. 3, 2014 Dec. 5, 2014 Dec. 8, 2014 Dec. 10, 2014 Dec. 12, 2014 Observed: Physical clear clear clear clear clear clear clear clear appearance Color colorless colorless colorless colorless colorless colorless colorless colorless Formulation # 3B Date Nov. 26, 2014 Dec. 1, 2014 Dec. 3, 2014 Dec. 5, 2014 Dec. 8, 2014 Dec. 10, 2014 Dec. 12, 2014 Observed: Physical clear clear clear clear clear clear clear clear appearance Color colorless colorless colorless colorless colorless colorless colorless colorless

TABLE 16 Stability of Formulations 4A, 4B, 4D and 4E Subject to Freeze/Thaw Studies Drug Cycle 1, Cycle 1, Cycle 2, Cycle 2, Cycle 13, Cycle 13, Substance t = 0 −20° C. 25° C. −20° C. 25° C. −20° C. 25° C. # 4A Date Feb. 1, 2016 Feb. 1, 2016 Feb. 1, 2016 Feb. 5, 2016 Feb. 5, 2016 Mar. 20, 2016 Mar. 20, 2016 Observed: Physical Clear Clear Clear Clear Clear Clear Clear Clear appearance Color Colorless Colorless Colorless Colorless Colorless Colorless Colorless Colorless # 4B Date Feb. 1, 2016 Feb. 1, 2016 Feb. 1, 2016 Feb. 1, 2016 Feb. 5, 2016 Feb. 5, 2016 Mar. 20, 2016 Observed: Physical clear Clear Clear Clear Clear Clear Clear Clear appearance Color colorless Colorless Colorless Colorless Colorless Colorless Colorless Colorless # 4D Date Mar. 14, 2016 Mar. 14, 2016 Mar. 14, 2016 Mar. 18, 2016 Mar. 18, 2016 Mar. 22, 2016 Mar. 22, 2016 Observed: Physical clear Clear Solidified Clear Solidified Clear Solidified Clear appearance Color colorless Colorless White Colorless White Colorless White Colorless # 4E Date Mar. 14, 2016 Mar. 14, 2016 Mar. 14, 2016 Mar. 18, 2016 Mar. 18, 2016 Mar. 22, 2016 Mar. 22, 2016 Observed: Physical clear Clear Solidified Clear Solidified Clear Solidified Clear appearance Color colorless Colorless White Colorless White Colorless White Colorless

TABLE 17 Stability of Formulations 4A, 4B, 4D and 4E Subject to 5° C. # 4A t = 0 Day 1 Day 8 Day 50 Date Feb. 1, 2016 Feb. 2, 2016 Feb. 9, 2016 Mar. 22, 2016 Observed: Physical Clear Crystals Crystals Crystals appearance Color Colorless Colorless Colorless Colorless # 4B t = 0 Day 1 Day 8 Day 50 Date Feb. 1, 2016 Feb. 2, 2016 Feb. 9, 2016 Mar. 22, 2016 Observed: Physical Clear Clear Clear Clear appearance Color Colorless Colorless Colorless Colorless # 4D t = 0 Day 1 Day 8 Date Mar. 14, 2016 Mar. 15, 2016 Mar. 23, 2016 Observed: Physical Clear Clear Clear appearance Color Colorless Colorless Colorless # 4E t = 0 Day 1 Day 8 Date Mar. 14, 2016 Mar. 15, 2016 Mar. 23, 2016 Observed: Physical Clear Clear Clear appearance Color Colorless Colorless Colorless

TABLE 18 Stability of Formulations 5A, 5B, 5C, 5D and 5E to Freeze/Thaw Testing Observation Formulation mg/ Storage Number Freeze/Thaw 20° C. RT 40 C. ID Spray pH condition of days Observation cycles (12 h) (12 h) (12 h) 5A 16 4.5 5° C. 28 Clear 28 Clear Clear Clear 5B 16 3.6 5° C. 28 Clear 28 Clear Clear Clear 5C 16 3.6 5° C. 14 Clear 14 Clear Clear Clear 5D 16 4 5° C. 14 Clear 14 Clear Clear Clear 5E 16 4.25 5° C. 14 Clear 14 Clear Clear Clear

As seen in Table 13-18, surprisingly, no crystals developed in any formulations and all formulations remained stable despite the harsh conditions.

Example 9

Spray Profiles

In order to determine the spray profile of Formulation 5A and 5C, it was subjected to standardized droplet testing. A challenge of creating a sildenafil sublingual spray formulation is that it must be capable of producing spray droplets that are over 10 microns in diameter. Spray droplets 10 microns or smaller could be inhaled into the lungs. The optimal particle size for sublingual spray droplets is from 20 to about 200 microns in diameter. It is desirable for the formulation to have droplet sizes near 20 because this increases the surface area and increased surface area exposure is one factor that contributes to a high bioavailability. Sublingual formulations should be able to maintain a consistent droplet size throughout its shelf life.

Droplet analysis was conducted using standard laser analysis procedures known by those of skill in the art. Droplet size distribution (Dv10, Dv50, Dv90, and Span were tested at two distances, 3 cm and 6 cm). Dv10 refers to droplet size for which 10% of the total volume is obtained; Dv50 refers to droplet size for which 50% of the total volume is obtained; Dv90 refers to droplet size for which 90% of the total volume is obtained; Span refers to distribution span (Dv90−Dv10)/Dv50; % RSD refers to the percent relative standard deviation. The results of these tests can be seen below in Tables 19 to 24. Applicant found during testing that formulations of the present invention yielded desirable droplet sizes for sublingual administration. The testing also revealed that the formulation dose remains consistent when administered with a spray pump.

TABLE 19 Spray Profile of Sildenafil Spray Formulation 5A, Particle Size at 3 cm Formulation #5A DV(10) DV(50) DV(90) %<10μ % Trans Span Actuation 1 21.13 48.74 110.6 0.1592 75.6 1.835 Actuation 2 21.97 44.73 96.98 0.00015 79.5 1.677 Actuation 3 21.37 42.87 93.52 0.02634 75.5 1.683 Average 21.49 45.45 100.37 0.06189 76.87 1.7316

TABLE 20 Spray Profile of Sildenafil Spray Formulation 5A, Particle Size at 6 cm Formulation #5A DV(10) DV(50) DV(90) %<10μ % Trans Span Actuation 1 26.6 58.64 118.2 1.241 71.3 1.562 Actuation 2 28.74 59.79 116.2 1.318 74.3 1.463 Actuation 3 29.14 56.97 107.3 1.410 74.3 1.372 Average 28.16 58.47 113.9 1.323 73.3 1.4656

TABLE 21 Spray Profile of Sildenafil Spray Formulation 5C, Particle Size at 3 cm Formulation #5C DV(10) DV(50) DV(90) %<10μ % Trans Span Actuation 1 20.34 43.49 100.6 0.00692 76.5 1.845 Actuation 2 20.6 42.5 95.69 0.00947 83 1.767 Actuation 3 23.43 47.09 101.3 0 86.3 1.655 Average 21.46 44.36 99.2 0.00546 81.93 1.7556

TABLE 22 Spray Profile of Sildenafil Spray Formulation 5C, Particle Size at 6 cm Formulation #5C DV(10) DV(50) DV(90) %<10μ % Trans Span Actuation 1 31.62 52.96 88.7 0 80.2 1.078 Actuation 2 28.92 53.42 98.37 1.194 75.9 1.3 Actuation 3 31.9 58.98 109.6 0.7866 85 1.318 Average 30.81 55.12 98.89 0.6602 80.37 1.232

TABLE 23 Spray Profile of Sildenafil Spray Formulation 1, Particle Size at 3 cm Formulation #1 DV(10) DV(50) DV(90) %<10μ D(4,3) Span Actuation 1 19.8 55.84 342.5 1.205 121.4 5.78 Actuation 2 20.17 51.61 263.1 0.2293 105.5 4.707 Actuation 3 20.39 72.27 453.8 0.269 161.8 5.998 Average 20.12 59.91 353.13 0.57 129.57 5.50

TABLE 24 Spray Profile of Sildenafil Spray Formulation 1, Particle Size at 6 cm Formulation #1 DV(10) DV(50) DV(90) %<10μ D(4,3) Span Actuation 1 24.57 55.86 487.2 1.133 151.2 8.282 Actuation 2 28.29 65.85 509.9 0 171.1 7.314 Actuation 3 25.4 54.14 423.1 1.263 130.9 7.346 Average 26.09 58.62 473.40 0.80 151.07 7.65

TABLE 25 Spray Profile of Sildenafil Spray Formulation 5A, Spray Pattern at 3 cm Formulation Ovality #5A Dmin (mm) Dmax (mm) Ratio Actuation 1 15.66 21.14 1.35 Actuation 2 15.65 20.86 1.333 Actuation 3 14.96 19.62 1.311 Average 15.42 20.54 1.331

TABLE 26 Spray Profile of Sildenafil Spray Formulation 5A, Spray Pattern at 6 cm Formulation Ovality #5A Dmin (mm) Dmax (mm) Ratio Actuation 1 22.2 28.31 1.275 Actuation 2 19.21 23.12 1.204 Actuation 3 19.63 24.42 1.244 Average 20.35 25.28 1.241

TABLE 27 Spray Profile of Sildenafil Spray Formulation 5C, Spray Pattern at 3 cm Formulation Ovality #5C Dmin (mm) Dmax (mm) Ratio Actuation 1 12.44 22.98 1.847 Actuation 2 12.96 17.2 1.327 Actuation 3 13.31 18.5 1.390 Average 12.9 19.56 1.521

TABLE 28 Spray Profile of Sildenafil Spray Formulation 5C, Spray Pattern at 6 cm Formulation Ovality #5C Dmin (mm) Dmax (mm) Ratio Actuation 1 22.21 26.81 1.207 Actuation 2 19.81 25.15 1.269 Actuation 3 20.9 28.12 1.346 Average 20.97 26.69 1.274

TABLE 29 Spray Profile of Sildenafil Spray Formulation 1, Spray Pattern at 3 cm Ovality Formulation #1 Dmin (mm) Dmax (mm) Ratio Actuation 1 20 26.4 1.32 Actuation 2 18.4 24.7 1.346 Actuation 3 18 25.7 1.433 Average 18.80 25.60 1.37

TABLE 30 Spray Profile of Sildenafil Spray Formulation 1, Spray Pattern at 6 cm Dmax Ovality Formulation #1 Dmin (mm) (mm) Ratio Actuation 1 14.7 28.5 1.931 Actuation 2 20.1 28.8 1.433 Actuation 3 15.5 21.7 1.401 Average 16.77 26.33 1.59

TABLE 31 Spray Profile of Sildenafil Spray Formulation 5A, Plume geometry data at 3 cm Formulation #5A Width (mm) Angle (°) Actuation 1 18.88 34.9 Actuation 2 16.48 30.7 Actuation 3 14.42 27.1 Average 16.59 30.9

TABLE 32 Spray Profile of Sildenafil Spray Formulation 5A, Plume geometry data at 6 cm Formulation #5A Width (mm) Angle (°) Actuation 1 26.43 24.7 Actuation 2 26.43 24.8 Actuation 3 21.97 20.8 Average 24.94 23.43

TABLE 33 Spray Profile of Sildenafil Spray Formulation 5C, Plume geometry data at 3 cm Formulation #5C Width (mm) Angle (°) Actuation 1 16.82 31.3 Actuation 2 16.48 30.6 Actuation 3 15.10 28.2 Average 16.13 30.03

TABLE 34 Spray Profile of Sildenafil Spray Formulation 5C, Plume geometry data at 6 cm Formulation #5C Width (mm) Angle (°) Actuation 1 21.63 20.4 Actuation 2 21.28 20.2 Actuation 3 18.54 17.5 Average 20.48 19.37

TABLE 35 Spray Profile of Sildenafil Spray Formulation 1, Plume geometry data at 3 cm Formulation #1 Width (mm) Angle (°) Actuation 1 25.3 45.4 Actuation 2 16.5 30.4 Actuation 3 16.8 31.2 Average 19.53 35.67

TABLE 36 Spray Profile of Sildenafil Spray Formulation 1, Plume geometry data at 6 cm Formulation #1 Width (mm) Angle (°) Actuation 1 31 28.4 Actuation 2 29.5 27.7 Actuation 3 16.8 15.7 Average 25.77 23.93

As can be seen in Tables 19 to 36, Formulations of the present invention provided excellent plume geometry and spray patterns.

Example 10

In Vitro Permeation of Formulations 4A-4F and 4H

The permeation characteristics of sildenafil formulations were studied using porcine buccal tissue. The porcine buccal model exhibits in vivo like morphological characteristics. Results of the in vitro permeation study can be seen in Table 37 below and in FIG. 1.

TABLE 37 In Vitro Permeation of Formulations 4A-4F and 4H through Porcine Buccal Epithelium Formulation ID Mean Flux SEM Mean P SEM 4A 0.69 0.147 7.20E−08 1.54E−08 4B 0.47 0.16 4.92E−08 1.66E−08 4C 16.79 3.095 1.75E−06 3.22E−07 4D 14.06 1.716 2.93E−06 3.58E−07 4E 13.59 1.427 1.42E−06 1.49E−07 4F 18.78 0.936 3.91E−06 1.95E−07 4H 15.06 2.564 1.57E−06 2.67E−07

As seen in Table 37 and FIG. 1, the addition of caprylic acid to formulations containing either propylene glycol or glycerol vastly improves the permeation of sildenafil through porcine buccal epithelium. Compare Formulation 4A to 4E (propylene glycol) where Mean Flux increased 20-fold and Formulation 4B to 4H (glycerol) where Mean Flux increased 32-fold.

Example 11

In Vivo Study of Sildenafil Sublingual Sprays in Minipigs

Protocol was a single dose crossover study. Five healthy male Yucatan minipigs were sublingually administered the formulations of Table 38. The minipigs were fasted overnight and through four hours' post administration. Administration was followed by a one week washout period. Blood samples were taken prior to administration and 2 (or 3), 5, 10, 15, 20, 30 min, 1, 2, 4, 6 and 24 hours postdose. Blood samples were measured for sildenafil concentrations via liquid chromatography-tandem mass spectrometry.

The following pharmacokinetic parameters were calculated: peak concentration in plasma (C_(max)) and area under the concentration-time curve from time-zero to the time of the last quantifiable concentration (AUC_(0-t)).

Results and Conclusions

Results of the pharmacokinetic and statistical analysis for the sildenafil formulations listed in Table 38 of the present invention are shown in Table 39.

TABLE 38 Summary of sildenafil formulations evaluated in the animal PK study. Formulation # M1 M2 M3 M4 M5 M6 M7 Dose (mg) 16 8 19 22.5 8 16 16 Sildenafil base 15.96 9.22 20 22 9.132 16.84 16.84 Ethanol 27 50 46 38 50 50 50 Caprylic Acid 2 2 2 2 3.68 Malic Acid 28.00 BKC 0.01 0.01 L-menthol 0.5 0.5 0.5 0.5 0.5 0.5 Sucralose 0.8 0.8 0.8 0.8 0.4 0.4 Glycerol 10 12 22 10 10 10 Water 29.04 13.97 11.1 6.34 14.187 6.24 9.92 1.5N HCL 13.35 13.221 6N HCL 7.45 8.21 12.19 12.19 Strawberry Type Flavor 0.15 0.15 0.15 0.15 0.15 0.15 Nat&Art 915.0543 U Total 100 100 100 100 100 100 100 pH 2.7 3.6 4.5 4.5 3.6 4.5 3.6

TABLE 39 Summary of pharmacokinetic parameters for sildenafil after sublingual administration of single doses of sildenafil formulations to Yucatan minipigs under fasted conditions. Formulation # M1 M2 M3 M4 M5 M6 M7 Dose (mg) 16 8 19 22.5 8 16 16 Conc. @ 2 min (ng/mL)  0⁽²⁾ 6.00⁽²⁾ 2.89 1.08 3.23 2.14 0.64 Conc. @ 5 min (ng/mL)  0.49 5.52 2.05 1.94 2.89 2.36 0.63 Conc. @ 10 min (ng/mL)  2.07 7.44 4.71 5.17 4.16 3.9 3.48 Conc. @ 15 min (ng/mL)  2.54 4.72 4.3 4.86 3.63 3.91 2.46 Median T_(max) (min) 30 10 10 10 10 15 15 C_(max) (ng/mL)⁽¹⁾  5.7 ± 1.5  8.5 ± 1.5   9.5 ± 1.3   6.3 ± 1.5  6.1 ± 1.4  7.9 ± 1.4  4.0 ± 1.4 AUC_(0-24h) (ng * min/mL)⁽¹⁾ 919.7 ± 1.1 801.3 ± 1.3 1797.8 ± 1.3 1075.4 ± 1.2 801.5 ± 1.4 894.7 ± 1.4 482.1 ± 1.3 AUC_(0-30 min) (ng * min/mL)⁽¹⁾  88.7 ± 1.5 158.3 ± 1.3  140.9 ± 1.4  112.0 ± 1.6 101.8 ± 1.6 135.0 ± 1.4  69.3 ± 1.3 ⁽¹⁾Geometric mean ± geometric standard deviation. Sample size is 5. ⁽²⁾Value reported as plasma concentration at 3 min postdose

Overall, the sildenafil peak plasma concentration of all formulations reached the maximum less than an hour postdose and then decreased to almost zero at 24 hours postdose. Specifically, the T_(max) of M2 to M7, each of which contains either caprylic acid, L-menthol or both, varied between 10 or 15 min, while M1, which contains neither caprylic acid or L-menthol, showed a T_(max) of 30 min. Compared to M1, M2 to M6, each of which contains both caprylic acid and L-menthol showed higher geometric mean C_(max) values. Particularly, M3 exhibited the highest C_(max) value of 9.5 ng/mL, and M7, which contains only L-menthol, exhibited the lowest C_(max) value of 4.0 ng/mL. The AUC_(0-24 h) values of all formulations were also evaluated. Among all, M3 and M4 exhibited the maximal systemic exposure after sublingual administration, with an AUC_(0-24 h) value of 1797.8 and 1075.4 ng*min/mL, respectively.

As part of the additional analysis, sildenafil formulations with faster onset were investigated. Surprisingly, when early plasma concentrations were evaluated among all sildenafil sublingual formulations, all formulations containing either caprylic acid, L-menthol or both showed earlier drug absorption, compared to M1. The plasma concentration of sildenafil varied from 0.63 to 5.52 ng/mL at 5 min postdose among M2 to M7, which was greater than the 0.49 ng/mL of M1. Specifically, M2 with 50% ethanol and 2% caprylic acid showed the highest plasma drug concentration at 5 min postdose. Similarly, almost all formulations showed higher early AUC values (i.e., AUC_(0-30 min)), compared to that of M1, indicating a faster absorption in the presence of caprylic acid and/or L-menthol. 

We claim:
 1. A sublingual spray formulation comprising: from about 2% w/w to about 35% w/w sildenafil or a salt thereof; from about 0.1% w/w to about 70% w/w of a solvent selected from the group consisting of water, ethanol, glycerin, propylene glycol, polyethylene glycol 400 and a combination thereof; and from about 0.1% w/w to about 60% w/w of at least one acid, wherein the formulation has a pH from 3 to about 5 and wherein w/w denotes weight by weight of the formulation.
 2. The formulation of claim 1, wherein the formulation is a simple solution.
 3. The formulation of claim 1, wherein the sildenafil is a salt selected from the group consisting of citrate, hydrochloride, halide, sulfate, phosphate, acetate, maleate, succinate, ascorbate, carbonate, mesylate and lactate.
 4. The formulation of claim 1, wherein the solvent comprises from about 0.1% w/w to about 50% w/w water.
 5. The formulation of claim 1, wherein the solvent comprises from about 10% w/w to about 70% w/w ethanol.
 6. The formulation of claim 1, wherein the solvent comprises from about 1% w/w to about 30% w/w glycerin or propylene glycol or polyethylene glycol 400 or a combination thereof.
 7. The formulation of claim 1, wherein the at least one acid is hydrochloric acid.
 8. The formulation of claim 1, wherein the hydrochloric acid may be from 0.1 N to 12N.
 9. The formulation of claim 1 wherein the formulation is propellant free.
 10. The formulation of claim 1, further comprising a permeation enhancer comprising caprylic acid.
 11. The formulation of claim 1, wherein the formulation does not contain a permeation enhancer.
 12. The formulation of claim 10, wherein the caprylic acid is at a concentration from about 0.1% w/w to about 10% w/w.
 13. The formulation of claim 10, wherein the caprylic acid is at a concentration from about 0.1% w/w to about 5 w/w.
 14. The formulation of claim 10, wherein the permeation enhancer further comprises a second compound selected from the group consisting of menthol, limonene, carvone, methyl chitosan, polysorbates, sodium lauryl sulfate, glyceryl oleate, caproic acid, enanthic acid, pelargonic acid, capric acid, undecylenic acid, lauric acid, myristic acid, palmitic acid, oleic acid, stearic acid, linolenic acid, arachidonic acid, benzethonium chloride, benzethonium bromide, benzalkonium chloride (BKC), cetylpyridium chloride, edetate disodium dihydrate, sodium desoxycholate, sodium deoxyglycolate, sodium glycocholate, sodium caprate, sodium taurocholate, sodium hydroxybenzoyal amino caprylate, dodecyl dimethyl aminopropionate, L-lysine, glycerol oleate, glyceryl monostearate, citric acid, peppermint oil and a combination thereof.
 15. The formulation of claim 14, wherein the second compound is menthol.
 16. The formulation of claim 15, wherein the menthol is at a concentration from about 0.1% w/w to about 5 w/w.
 17. The formulation of claim 15, wherein the menthol is at a concentration from about 0.1% w/w to about 1 w/w. 